Singler line FFMPEG cmd to Merge Video /Audio and retain both audios

Question

I have a project that requires merging of a video file with another audio file. The expected out put is an video file that will have both the audio from actual video and the me

Answer 1

I don't think extracting the audio from the video is necessary. We can just use -filter_complex amix to merge both audios:

ffmpeg -i videowithaudio.mp4 -i audiotooverlay.mp3 -filter_complex amix -map 0:v -map 0:a -map 1:a -shortest videowithbothaudios.mp4

-filter_complex amix overlays the audio from the first input file on top of audio in the second input file.

-map 0:v video stream of the first input file.

-map 0:a audio stream of the first input file.

-map 1:a audio stream of the second input file.

-shortest the length of the output is the length of the shortest input